I have played many different RPG combat systems I've enjoyed, and I think the running theme isn't so much whether it's real time or turn based but more-so if it requires strategic thinking. I enjoy the simplicity of controls where I don't have to memorize an entire keyboard's worth of hotkeys or go 5 menus deep into something to perform an action, but where complexity is still present. I'll list a few RPGs where the battle system really stood out for me and why I liked it:
Final Fantasy XII This was an evolution of the active-time battle system. You could move around the map, switch between party members, automate everyone's actions through simple AI called "Gambits", and was quite enjoyable because with proper Gambit set-up you could make most casual enemy encounters automated and just watch your party work, but leaving boss fights up to AI was a death sentence, you really had to knuckle down, learn weaknesses, and counter all kinds of debilitating moves they would conjure up. Add in to the mix a license board, technicks, summonable espers, quickening attacks, chain kills, and the complexity really piled up in a good way that gave you a lot of choices to make in battle.
Dragon Quest VIII Simplicity perfected. A 100% turn-based combat game that nonetheless retained challenge and interesting mechanics. It really put a lot of effort into making challenge about properly making the most of each action rather than twitch mechanics. Everything is very easily explained and straight forward, hitting the attack button attacks, hitting the magic button uses magic, and so on. It also had some unique additions such as using a turn to raise tension to release a more powerful attack, summoning a monster party you had captured for a few turns, and a lot of unique special moves that give a new spin on the classic formulas.
Baldur's Gate Basically a turn-based RPG disguised as real-time. If you attempt to play through the whole game without ever pausing to give commands... you're gonna have a bad time. Every action in the game revolves around turns, and it's up to you how frequently you choose to stop and plan out your next move. Add in the complexity of AD&D 2e and you have a huge variety of classes, races, equipment, skills, magic, and game mechanics that really layer in a well designed party-based RPG
Mount & Blad WarbandA game that's heavily action oriented without once sacrificing it's dedication to statistical complexity. Each soldier has their own innate stats based off their unit type, which also is complimented by their gear, and morale. Your own character as well as special companions can even be individually geared up and have their stats raised as you deem fit, and in battle you never have direct control over anyone but your one character but can issue commands at your leisure. It's the perfect marriage of action-based gameplay and stat-and-skill based gameplay.