Great question, and I have been in a similar boat before.
A few questions come to my mind in regards to which gimbal would be best for you: How close are you to the subject in most cases? What style of video are you doing (documentary-style footage only/no audio, performance recap/audio needed, etc.)? What style of music/what vibe (for lack of a better word) are you going for?
First and foremost, make sure you're working with a lens that has IS (Image Stabilization). If you don't have this, then you will have to resort to several other frustrating and possibly expensive options, only to decide that you still need a lens with IS. Get this first.
I have used a Shoulder Rig for a lot of the concert footage I have shot. The rig I got online was only around $150 from FilmCity. Look it up, it's great quality for a great price. But the main reason I bought this was because I was limited to this option since Follow Focus on my manual focus only rig was required, and I could use one hand to follow focus. This may not be a necessary rig for you if you have Auto Focus as an option. Also, get ready to feel the soreness in your arms and neck with a shoulder rig.
I have used a cheaper version ($100) of the Glidecam before, but this can only really be used for specific shots, and specifally wide angle pans or zooms. You probably wouldn't want all of your footage to look like you're walking around a venue, but rather focusing on the close-ups of the artists.
I have decided that the options that have the most flexibility and undeniable quality are 3-axis gimbals, namely the DJI Ronin M3 ($899) and Zhiyun Crane V2 ($399). Both operate very differently, but doing some research on these and looking at user footage is essential. There is certainly a learning curve to using gimbals like these. But they are some of the steadiest around for the lowest cost.
Hope this helps!