I have had and still run several Lux receivers as a big fan of their sound..
Consensus is the R-117 is the bad boy on the block. I've never had one. Seems like lots of power under the hood for a receiver.
Seems for that much power and having read of issues with these I'd rather get a separate power amp and run a R-113 as the preamp.
R-115. I have 2; One as a main daily driver and one in the closet as a backup and for future parts if needed.
Love this receiver. Lots of inputs and options. Good tuner. Good sound. Remote control. Been a good unit for me for years.
R-113. For only 35wpc a nice sound, good tuner, good inputs and outputs. and can be used as a preamp to run a larger amp. Run in the bedroom and like it.
R-104, 105, 106. Ok units. Touches on the smooth Luxman sound. Not in the same league as the larger R units. R-106 has had power relay issues and runs hot at times to make power to the speakers.
RX-102. Very nice sound. Most tube like out of all my Luxmans. I use it daily and have enjoyed it. Don;t let the 70wpc fool you, it has a nice sound and powers some B&W 685's very nice.
R-1120A. My favorite of them all and I would believe what they say about it being one of the best ever "monster" receivers.
Mine is currently in the closet awaiting power board repairs for some rectifiers that burned when some speakers shorted out.
Though a large receiver, it has great power, sound, silver looks, build quality and in-out options. My favorite of them all.. I will keep it forever probably.
That's my experience with Luxman's. I fell in love with the "Luxman sound" from day one and am always on the lookout for a good deal on an old unit.
Good luck and hope you enjoy whatever you decide to get.