Does anyone have any solid experience and recommendations for a drop bar hydro group set?
Plus an affordable place to buy?

I have 11 speed 105 on my Arkose. It’s ace, shifting is spot on and the brakes stop me! Came on the bike though, so can’t help as to where is best to buy from.

As above 11 speed 105 on an arkose, its faultless

I’ve had SRAM HydroR brakes on for nearly 18 months now. Very good, shift well and pretty good ergonomics.
I’m waiting for Etap Hydro WiFli before going any more.

Suspect either SRAM or Shimano are fine. Depends on what shift type you like.
Also SRAM interchanges with its own MTB stuff generally. Shimano appears to be less so. I may be wrong.