It depends.
HT can be quite versatile for bike packing etc, but an XC FS would be a better ride (if you choose carefully and put a dropper on).
Edit – Oh yeah and road bike, tourer, gravel bike, trials bike, bmx, dirt jump/street bike, track bike, CX bike are all valid options too. It depends what other riding you’d like to do – do you go to trails locally and wish you could get around them faster? XC FS would do that (and be fun if you choose well). Do you just want to play? Get a jump bike or something. Do you want to go further afield on less severe trails or road? Well, you get the picture.
Don’t buy a bike, buy a means of doing whatever riding you think you’re missing out on with your current bike.
Edit 2 – for me the second bike would be a commuter, racks, mudguards and tyres capable of a bit of rough stuff, dynamo lighting and built for reliability not out and out speed. It’s the bike I ride the most/enjoy the least, but it’s very useful.