I have no experience with the .375 Ruger, however I did own a Smith & Wesson Model 1500 (which is now the Howa) for 25 years, and it was a good one. Mine was chambered in 7mm Rem Mag and never let me down. It traveled with me to Namibia in 2014 and except for the first day where I had to use my PH's rifle due to ours not arriving in Windhoek till the day after we got there, it performed as it always does and added a baboon, warthog, hartebeest and impala to my trophy room.
Two years ago, I decided that I really wanted to replace it with a Tikka T3 and there have been pros and cons with that. The S&W had a hinge-plate which I prefer over a detachable magazine like the Tikka has. Not sure if Howa uses a DM or not. The light weight of the Tikka causes noticeably more felt recoil than the 1500 to me. Tikka action is far nicer and it is a slightly nicer shooting rifle to me.
Based on 25 years with my Model 1500, I think you'll be happy with the Howa!