I found Ethol LPD to be a Metol free, easy to use, long lasting, available, economical and tone flexible developer. For example; I stored distilled H2O mixed LPD developer in 1L hard plasic water bottles for 8 months. Last night I used developer from an unopened bottle. The developer performed normally. LPDs tray capacity is higher than Dektol and has a longer shelf life. Dilution has minor effects on image tone which is better than nothing.
Liquid concentrated developers, with the exception of ECO 4812 and Liquidol, have short (2/3 month) shelf life after breaking the seal. I wonder what you give up to get long life from liquid developers? Therefore I use LPD and 130.
I've used 130, PQ, Dektol, ECO 4812, Liquidol, Arista Liquid Developer/Freestyle, Neutral WA, Universal, ECO-Pro, and a few others. Liquidol and ECO 4812 do last a long time. I like 130 but I did get stains (glow) when the tray solution was getting exhausted. Cool temps (below 70) slow down 130's development. 130 is a bit softer than Dektol/Arista, & PQ. 130 is not the best price value.