Turnigy 5000mAh 3S 11.1V LiPo battery pack
Lipo batteres (lithium polymer), and in particular 3S batteries, are the ones I recomend for portable ham radio such as BOTA or SOTA. They are low cost, light weight, compact and efficient for portable operations. When fully charged, their voltage is 12.6V, within the range of most transceiver manufacturers. When discharged, they can be around 11V, which is sligtly outside the 13.8V+-15% range of some manufacturers. However, that range is provided by manufacturers very cautiously and for full power operation. When operating portable, however, it is seldom efficient to use more thaan 20 or 30W, and in this range transceiver voltage is probably not so critical. Undervolting is common in PC modding for instance in order to gain efficiency. If you go for Lipo batteries, I would try the 3S configuration.
I bought 4 battery packs from Hobbyking in 2019, and they are holding out great. I started using LiPo batteries for SOTA because of their light weight. Now in my ham radio trolley, in which weight is not so critical, I still prefer them to any other type, and I have used all kinds of batteries, from NiCd and NiHh to lead acid and LiFePo4.