It really depends on what you are looking for and/or what kind of signal level you are getting at the location. There are actually 3 choices;
Signal booster; takes existing low signal and boosts it. If you have very low signal it probably will only help a little bit but if you get decent signal outdoors at that location and just indoor is a problem it probably will solve the issues as long as you can locate it near an outer wall or window.
Cellspot; This is just essentially a router but is enhanced for Wi-Fi calling so no matter if someone is gaming or hogging all the bandwidth Wi-Fi calls will take priority. Of course this is only supporting Wi-Fi calling and is using your internet connection.
LTE Cellspot; This essentially puts an LTE tower in your house. It uses your internet connection as it's backhaul. Good part is that you won't have to change anything on your phone and also anyone friends or family on T-Mobile will be able to use it. That for some is the drawback in that while it only has a range of around 3000 sqf anyone on T-Mobile can use it if they can reach it. However if you want to reliably make calls in your home and not use Wi-Fi calling what better than to have your own tower.
I have the Cellspot, when I first moved to my current location due to the geography and trees I couldn't get a reliable signal so signal booster wouldn't have been reliable so got what is a great router and has enhancements for Wi-Fi calling. I used it for about 3 months for calls until they turned on Band 12 (Extended LTE) in my market which solved my signal issue. I still use it as a router and if I happen to be on Wi-Fi it still will take calls.