UF-B or THHN in conduit for hot tub feed

I am a serious DIY and am adding a circuit for a hot tub.
The GFCI breaker panel for the tub will be 125' from the main breaker panel and will all runs will be out doors. My plan was to run 6 AWG between breaker panel and GFCI panel for the tub in 1" PVC conduit secured to the outer wall of the house. My question is do I need to run 6/3 UF-B or can I run 4 individual wires of 6 AWG THHN stranded?
Thanks
Scott

You MUST run THHN/THWN conductors since the outdoor portion of wiring to a hot tub MUST have a green insulated ground. The bare ground in UF cable does NOT meet this code.

I must STRONGLY suggest you read up on Art. 680 of the NEC. An outdoor hot tub is treated almost exactly as a pool and the codes are specific and many. This is not a place to mess around if you don't know what you are doing.

Thank you, I was sure that was the case but wanted another input.
Have a copy art 680 and am reading through it.
Thanks again.