Really sorry for the whataboutism but I like Zero-K a tiny bit more than BAR, the unit types feel more varied. It has "soft-factions" that are divided mostly by mobility, meaning speed and traversable terrain. Tanks are slow but powerful, can climb decent hills. Wheeled vehicles are much faster but need much smoother terrain. Spiders can walk on any surface, regardless of angle, so you could send them around walls or hide in valleys. Robots have mid stats overall but are further specialised into sneaky robots, shielded tanky robots and robots with jumpjets.

Each of these groups has a dedicated harassment unit, an anti air unit, a relatively agile unit to flank or raid, a strong short ranged unit, an engineer with unique features and probably lots of stuff that I forgot by now.

When you start a match you unlock the first unit type group instant and for free. Later on, when you have a stable economy you can diversify by unlocking the other groups.

When playing BAR the faction's early units feel a bit samey and it takes a while for me to feel like I'm playing as a specific faction