Yeah so what do you want here? If it's to be something portable and/or temporary then why not just tether phone, or there's the USB stick option. If you care about max performance and things like carrier aggregation working well to secure the most bandwidth from cell tower then you want something high spec (high CAT). For best performance you may want an external directional antenna that points to the cell tower and to optimise signal indicators for that. So yeah it all depends really.
In my case we use B818-263 in its bridge mode (perhaps not truly a bridge but it acts like this) and have OpenWrt router (RT3200) connect to that over wan port. OpenWrt router gets a WAN IP from my ISP and all works well. Get excellent signal stats to cell tower but spent ages optimising positioning and location.
With variable bandwidth connection if you want SQM you may like to look at the CAKE autorate threads on this forum.