Yup, love doing excels/ sovereigns. We just got a brand new sovereign based with us and the thing actually has a light in the lav service compartment.
Challenger 300s are pretty painless although the 600s are easier to hook up to if you're using a tow bar. The 300s also look better in my opinion, especially the cockpit window. We have one based with us, owner-piloted too.
Hawker 4000s are also super easy with everything, especially the nose gear pin.
Love Gulfstreams except for loading bags can get kinda annoying if the pax didn't pack light because of the baggage door height. Same with the Global Express
Ahh the Falcon 50 lav, all the way on the very bottom of the fuselage... Yup I hate em too. Thankfully they fixed that on the 900s/ 2000s and beyond. We have two based with us and I was training a new guy on servicing the lav and the clowns at their previous destination must've pulled the chain after they put the cap back on; he unscrews the cap and it dumps everywhere. The trainee didn't show up the next day and we never saw him again.
Least favorite:
Not even gonna start talking about beechjets and what a pain in the neck they are. Except for the guys I worked tonight who had an old school Diamond and transferred the fuel into the trunk as I topped the wing off... You da real MVP
Turbo commanders are also a pain as far as fueling but we have one based with us so it's like second nature to me now. Same thing with MU-2s especially when that guy who absolutely has to do a GPU start shows up and you fear for your life when it's time to pull the plug.
A-star helicopters are only annoying when I get a top-off fuel order and you never know when it's full till it's too late.
Up until a week ago, we had a HondaJet based with us and after the new airplane excitement wore off, we started to hate it. Fueling it is the same as the trunk on the beechjet, only there's no recess into the fuselage and you're left with the cap just dangling there and risking a paint scratch. What a dumb design.
Gotta pump even slower than the beechjet too.