What kinds of profiles do you like? Do you want a second hand, vintage set that may be more unique? What color palettes are you looking for? What boards will they go with? Do you need RGB shine through keycaps?
That being said, my vote is always for a Signature Plastics SA profile keycap in whatever theme fits the board.
Yeah this question requires a lot more detail for a good answer. But in general if you are starting out I wouldn't reccomend SA because it's more an aquired taste, and for a lot of people it's too high up. I would recommend buying cherry keycaps. JC studio/leekbrothers if you are on a small budget (leekbrothers is the taobao name) and if you have more of a budget a lot of vendors have gmk instock often at discounts if you want to pick them up (Just pick good vendors, in the U.S novelkeys or cannonkeys, in the EU oblotzky is amazing for some reccomendations)
If you do like SA then absolutely go with signature plastics, the quality is very good.