Tile set suggestions?

[GamerBoyFranklin]

I've been looking to "spice" up the visuals in my game lately.
While looking through old r/OpenTTD I started seeing a lot of screenshots with really neat scenery and extra buildings.
I've personally never delved to deep into OpenTTD's modding scene, so any help would be greatly appreciated!

[kamnet]

There's really no "bad" sets, it's all mostly individual likes or dislikes.

I'd suggest looking at the NewGRF List to see links to various forums for each type of NewGRF available, where you can decide for yourself what you'd like to try playing with. Most NewGRF packages can be used with each-other, the few that are restrictive will let you know what they're not compatible with and will usually disable themselves. Personal aesthetics and your own imagination are your only limits.