I'm not sure which way to go with the combat mechanics. The game is a roguelike.

Which would you reccomend? (if you have an unique idea let me know in a reply or PM)

Here's the options explained:

1. Skill Based: Fight only with skills, also involving combos.

2. Turn Based: Player and enemy take turns to attack/dodge (Like Pokemon or Undertale)

3. Click Based: Click on the enemy and it takes damage. Nothing simpler.

4. Task Based: Complete a task/series of tasks to attack the enemy (Press a series of keys, solve a puzzle, etc)

5. Other: Got a better idea? Reply.

I have fond memories of turn based RPG's where you use a wide variety of abilities (are these abilities what you meant by fighting with "skills"?). I just feel like there haven't been many I actually liked in a very long time. There are great tactical rpgs, of course, which include these turn based RPG game mechanics along with a map, adding more importance to good positioning than to picking the right skill. But I feel like I need one of the old turn-based RPGs, where the skill you choose actually matters and isn't an obvious choice every time. Maybe I should jump back into Darkest Dungeon now that it's out of early access.

Combat mechanics should fit and compliment your game. For example Nethack, Fallout (1 & 2), World of Warcraft and Shadow of Mordor are all for me great RPG games with very distinct combat mechanics. If you change the mechanics in any of those game the result would be completely different game (see Fallout 3 & 4 :)).

If you are unsure where to go try to quickly prototype as many kinds of combat as you can and play-test them. This should give you an idea what fits your game and what not.

More information would be helpful. Like what's the party size (1 means a soptisticated system can be used while 8 means a simple but fast is obligatory), what's the theme (SF means range weapons which might works better with different mechanics), how many enemies simultaneously the player will face (the more of them the less desirable a classic turn based is), how often the combat will be (if rare task based might make sense), etc.