Which trading plateform to make cavalry? There are many companies offering crypto-currencies exchange service.

But many of them have a gap in their currency list. Some other have a strange complexity.

All wallets are not systematically stored in the same point making things complicated.

Is there a good list of companies (websites) offering a simple exchange service, optionally giving wallet storage and not requiring a PhD to use?

The goal is to make currency exchange relatively offend.

(after comparison, the only that makes the difference is Kraken)
I suggest you to read this writeup https://blockgeeks.com/guides/best-cryptocurrency-exchanges/
it presents well known platforms with their pro&amp;cons e.g:

Coinbase

Backed by trusted investors and used by millions of customers globally, Coinbase is one of the most popular and well-known brokers and trading platforms in the world. The Coinbase platform makes it easy to securely buy, use, store and trade digital currency. Users can purchase bitcoins or Ether from Coinbase through a digital wallet available on Android &amp; iPhone or through trading with other users on the company’s Global Digital Asset Exchange (GDAX) subsidiary. GDAX currently operates in the US, Europe, UK, Canada, Australia and Singapore. GDAX does not currently charge any transfer fees for moving funds between your Coinbase account and GDAX account. For now, the selection of tradable currencies will, however, depend on the country you live in. Check out the Coinbase FAQ and GDAX FAQ

Pros: Good reputation, security, reasonable fees, beginner friendly, stored currency is covered by Coinbase insurance.
Cons: Customer support, limited payment methods, limited countries supported, non-uniform rollout of services worldwide, GDAX suitable for technical traders only.

Kraken

Founded in 2011, Kraken is the largest Bitcoin exchange in euro volume and liquidity and is a partner in the first cryptocurrency bank. Kraken lets you buy and sell bitcoins and trade between bitcoins and euros, US Dollars, Canadian Dollars, British Pounds and Japanese Yen. It’s also possible to trade digital currencies other than Bitcoin like Ethereum, Monero, Ethereum Classic, Augur REP tokens, ICONOMI, Zcash, Litecoin, Dogecoin, Ripple and Stellar/Lumens. For more experienced users, Kraken offers margin trading and a host of other trading features. Kraken is a great choice for more experienced traders. Check out the Kraken FAQ

Pros: Good reputation, decent exchange rates, low transaction fees, minimal deposit fees, feature rich, great user support, secure, supported worldwide.
Cons: Limited payment methods, not suitable for beginners, unintuitive user interface.

The Ultimate Guide To The Best Cryptocurrency ExchangesSave

Cex.io

Cex.io provides a wide range of services for using bitcoin and other cryptocurrencies. The platform lets users easily trade fiat money with cryptocurrencies and conversely cryptocurrencies for fiat money. For those looking to trade bitcoins professionally, the platform offers personalized and user-friendly trading dashboards and margin trading. Alternatively, CEX also offers a brokerage service which provides novice traders an extremely simple way to buy bitcoin at prices that are more or less in line with the market rate. The Cex.io website is secure and intuitive and cryptocurrencies can be stored in safe cold storage. Check out the Cex.io FAQ

Pros: Good reputation, good mobile product, supports credit cards, beginner friendly, decent exchange rate, supported worldwide.
Cons: Average customer support, drawn out verification process, depositing is expensive.

The Ultimate Guide To The Best Cryptocurrency ExchangesSave

ShapeShift

ShapeShift is the leading exchange that supports a variety of cryptocurrencies including Bitcoin, Ethereum, Monero, Zcash, Dash, Dogecoin and many others. Shapeshift is great for those who want to make instant straightforward trades without signing up to an account or relying on a platform to hold their funds. ShapeShift does not allow users to purchase crypto’s with debit cards, credit cards or any other payment system. The platform has a no fiat policy and only allows for the exchange between bitcoin and the other supported cryptocurrencies. Visit the Shapeshift FAQ

Pros: Good reputation, beginner friendly, Dozens of Crypto’s available for exchange, fast, reasonable prices.
Cons: Average mobile app, no fiat currencies, limited payment options and tools.

Poloniex

Founded in 2014, Poloniex is one of the world’s leading cryptocurrency exchanges. The exchange offers a secure trading environment with more than 100 different Bitcoin cryptocurrency pairings and advanced tools and data analysis for advanced traders. As one of the most popular trading platforms with the highest trading volumes, users will always be able to close a trade position. Poloniex employs a volume-tiered, maker-taker fee schedule for all trades so fees are different depending on if you are the maker or the taker. For makers, fees range from 0 to 0.15%, depending on the amount traded.

For takers, fees range from 0.10 to 0.25%. There are no fees for withdrawals beyond the transaction fee required by the network. One of the unique tools on the Poloniex platform is the chat box which is constantly filled with user help and just about everything. Any user can write almost anything but inappropriate comments are eventually deleted by moderators. It can sometimes be hard to distinguish the good advice from the bad, but the Chatbox is a great tool that will keep you engaged.

Pros: fast account creation, feature rich, BTC lending, high volume trading, user-friendly, low trading fees, open API.
Cons: Slow customer service, no fiat support.