How to specify a Rules condition related to select list values?
Below is a sample of a rule (in Rules export format) that should allow you to specify a Rules condition relation to a specific value selected via a selection list (and when a new node is created):

{ "rules_new_node_with_special_optionlist_value" : {
    "LABEL" : "New node with special optionlist value",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules" ],
    "ON" : { "node_insert" : [] },
    "IF" : [
      { "entity_has_field" : { "entity" : [ "node" ], "field" : "field_optionlist" } },
      { "data_is" : { "data" : [ "node:field-optionlist" ], "value" : "C" } }
    ],
    "DO" : [
      { "drupal_message" : { "message" : "A new node got created with option list value = Custom" } }
    ]
  }
}


Some more details to further explain the above above sample:


The Rules event I'm using is "After saving new content".
In my case I have a selection list field with machine name field_optionlist.
This field actually has 3 possible values, like so:


A (=Advanced).
B (=Basic).
C (=Custom).

As a sample, I decided to use as condition "The selected value must be Custom".
If that value is selected, then (as Rules action), a message is shown like A new node got created with option list value = Custom (feel free to change that to whatever Rules action, this is how I often "unit test" new rules I write).


The "clue" to make this rule work is the condition Entity has field. That's also what is mentioned in the Rules UI when you're adding a "data comparison" condition: somewhere it says "The data selector helps you drill down into the data available to Rules. To make entity fields appear in the data selector, you may have to use the condition 'entity has field' (or 'content is of type')". I wouldn't be surprised if that is what you are missing in the rules conditions you tried so far ...

Note that I've not added a Rules condition here about selected content types, that's probably an extra condition you might want to add also. But if the selection list field is only used for the content types you're interested in, then the Entity has field condition should be sufficient already.

For a video tutorial that illustrates the importance of this Entity has field
condition, refer to Data types and data selection, especially what is shown between about 13:30 and 17:30 in that video.