Welcome! And your dad has a good son!!
USP vote for me also! Good Son! I just turned 57 last month, got a jar of Miller's hot bologna and wife treated me to 5-Guys hamburgers?. But I know I'm still loved!
Also for a Mp5 RS, consider some fo the last of the Turkish MKE's before they may never be seen again. I saw a used one for $1200 on arslist the past few days. I paid more and an very pleased with mine. I was able to fire one FA and it ran like a champ. I realize they are no genuine HK but licensed, however, they are great for their price point and range use. I just need a second mortgage to be able to keep feeding it as often as I like firing it.
With xxl hands and being in love with the USP series for decades now, I can say that I enjoy the HK45T equally to my USPT and the groups are a bit tighter but that could be attributed to the Heinie sights. Read the thread for more details if interested.
USP 45 Tactical. I think the USP is a more rugged looking gun. Some people make noise about the grip size, but even with my small hands, I can get a good grip on it.