Going to be personal choice, probably based on gut feel. I don't think many will have tested both, and won't have for some time.
I went for Wheeltop based on a few things, which may or may not be accurate or correct... but my own twisted logic:
- Mixed reviews on Ltwoo support - I so far I have contacted Wheeltop twice and they were helpful, but most helpful via WeChat, which in itself is a bit of a pain if you don't speak Chinese
- Adjustability and choice of multi-geared options. I intend to run two Wheelsets, one 11 and the other 12 speed
- Battery located on the derailleur, very minor difference and hardly an advantage now it isn't easily swappable
- I was also able to find Wheeltop on Taobao direct from the parent company which saved some money
I have only used Wheeltop, and it's my first ever electronic groupset, so although happy I don't have anything to compare against, so not in a position to say 'how good' it is.