The antenna will be key here, the core electronics doing the radio receiving will be broadly similar as the TTIG. Buy an antenna from an actual radio supplier, directly or via eBay. Not from Amazon, it’s filled with cheap bits of bent wire that can make you go backwards.
If you search the forum / Google, you can find instructions on hacking a TTIG to add an antenna connection.
Otherwise, for a moderate number of nodes, both RAK gateways are good, I’ve got one of each but tend to use the small blue one as it hurts less when I knock it off the edge of my cluttered desk - not sure there’s a point of paying for the metal case if you are in charge of where the gateway is located - if staff can reach it then metal cases help protect them from acts of random stupidity.