What kind of language would you suggest for an University compiler project?
I think you are trying to achieve too much in a single exercise. It would, in my opinion, be better to separate the compiler construction part of the exercise from the comparative language part.

Good code generation and optimisation are difficult for some of the additional features you have cited. In my view it is better that students learn to do some decent lexing, parsing, optimisation and code generation before having to handle some of the more complex features of languages. 

If you create a portmanteau of a language you end up with lots of examples of rotten and partially functioning compilers which do not help them learn.

It also matters what the target language you are going to use. Are you asking them to generate CIL, Byte Code, C  or some other output format? Each of these has different pedagogic reasons for their choice.

Choosing a language to build an example compiler for is like choosing a first programming language. There is no right choice.

To start building compilers I often recommend compiling something like Pascal or even simpler. (The choice of compiler implementation language depends on the tool set you choose to teach.)