Li-Ion is best choice for power density, capacity.
NiMh is cheaper. SLA are cheapest.
cost is usually inverse with ESR and proportional to Ah capacity, which affects load regulation voltage. Some cheap Chinese no spec LiPo batteries may seem to be a bargain, until you discover flaws which affect life cycle limit from temperature rise, but LiPo fom reputable sources may be best if price is right.
NiCd were low ESR but now are obsolete due to environmental concerns, with minor exceptions.
All important specs can be found here.