Rightly or wrongly, I solder spade connectors to the wires on all my batteries, then solder the connector to the battery terminal. On the other end I use Deans connectors, so I can use any battery in any model. My chargers also have Deans connectors, as do my motors and ESCs, so everything is standardised throughout I arrange the male and female connectors so I can't accidentally connect anything up wrongly. I have had no problems with any battery by soldering to the terminal, but I do use a 60W iron. Soldering the spade connector directly to the battery terminal practically eliminates the risk of a poor connection, and the Deans connectors are a very positive type of connector
The photos below show one of my smaller SLA batteries, and the inside of my pusher tug showing the connections. The bare plug at top right connects to the battery.
The chart under the battery is my charging record, where I note when each battery was charged.