As sloopy wrote, 800XL and 130XE are either good machines.
My two cents:
Cart port position: 800XL
Design: 800XL and 130XE are both beautiful and original, it's a matter of taste.
Keyboard: it's a matter of taste but you must consider that 5 kind of keyboards exists for 800XL (in only three years lifespan!) and, if I am not wrong, at least 2 kinds for 130XE.
Memory: 130XE has 128KB instead of 64KB, usuful for few games (but now AA user ctirad sells an external 320KB low cost memory expansion for 800XL)
Video ouput: 130XE has also s-video (but with a simple jumper 800XL can have s-video too, but with a bit lower quality)
Quality: 800XL has a better building quality. Moreover, some XL's have all ICs socketed, so they are easier to repair and upgrade.
Basic: 130XE has bug free Basic rev. C (but you can replace 800XL Basic rev. B IC with a rev. C - anyway, if you like Basic programming, nowadays everyone uses the fast, compatible and compilable Turbo-Basic XL so Basic's revision is unimportant).