I have both a Mainland and a Goldtone (I just bought my sister's as she wants an 8 string Lanikai & I was only too pleased to help her out!)
I bought my Mainland 18 months ago & was SO happy with it, that when I formed a uke group in my home town - half the members wanted one, so I brought in 12 from Mike at Mainland for the group, family & friends!!
Mainland used to do Banjo ukes, but they had problems with their suppliers so only sell 'parts' now.
If you find a Mainland for sale, grab it - as it is a very playable and affordable instrument that is not heavy. THey don't come on the market very often tho! It has less metal 'clips' than the Goldtone & others, which makes them much lighter. With less 'clips', they are also very much more comfortable to play, as the 'clips' are not sticking in your arm or body as you play.
The Goldtone Concert is much heavier as it has twice as many 'clips' but I find that the action is
much lower & easier for me to do Barr chords (I have arthritis & find it difficult to press hard enough with the thumb to get clean chords.) I am trying to pickup the Formby style of playing & am finding it easier on the Goldtone than the Mainland, which has slightly higher action (I am guessing that this COULD be lowered a bit, but I haven't tried at this point.)
If you can't find a Ukulele Shop with lots of Banjo Ukes in it to actually try out yourself, I would suggest that you join a uke group who's members
have banjo ukuleles & 'try' as many different brands as you can!
Maybe put a post up here to see if there are any Banjo Uke players anywhere near your town that you can catch up with?
DON'T buy any that you haven't tried - and definitely don't buy a Rally BU from ebay unless you can actually play it first ....... a friend in my group here bought one with the big resonator back & has had major setting up issues with it - he has never brought it to our group since and it rarely sees the light of day!
There are some terrific vintage ones out there - a British guy called Jasperhappy puts up videos of the vintage banjo ukes that he sells on ebay, which helps buyers make a decision.
Vids of his antique banjo ukes that he restores & sells on ebay
https://www.youtube.com/user/jasperhappy
Here is his advice on buying banjo ukes
Fellow member Jnobianchi is a terrific banjo uke player & has heaps of vintage banjo ukes - I am sure he would assist you in your search for a good banjo uke!
Good luck in your hunt
Roberta