TWRP has long been the leading custom recovery for Android smartphones. You can flash ROMs, manage local files, install custom themes, and backup/restore your whole device. TWRP is also great because it's easily ported to other devices, and as evidence of that, the project has begun supporting three new phones.
First up is the Xiaomi Mi MIX, which made headlines late last month for its edge-to-edge screen. Next is the Huawei Honor 8, which we reviewed back in September. Finally we have the Lenovo K30-T (also named Lenovo K3), which was actually released back in 2014.
As always, consult the page specific to your device before attempting to install the recovery. You can find links for all these devices at the source links below.