Convenience means easy and wuick to make up with minimal fuss, to me. Over the past 26 years I've only used 3 negative developers , initially Rodinal and Xtol but more recently Pyrocat HD.
For many yearsv I used replenished developers, Microphen, D76 and later Adox Borax MQ this is the most convenient way of working, the developer is always ready for use. Volumes needn't be large I prefer a minimum of 2.5 litres working solution and used large commercial deep tanks for over a decade at work, this is the most economical and consistent way of working. When Xtol was released I switched, this is even better for small scale replenishment as it's replenished with fresh developer rather than a dedicated replenisher. I tended to process my personal work in Rodinal and commercial work in Xtol but both gave excellent results.
However convenience has other connatations and it was more convenient to take Pyrocat HD with me to Turkey, a small volume of concentrate processes a lot of film, for travelling I make Part A double strenght and buy the carbonate for Part B locally.
I've stopped using Xtol because travelling made it impractical, leaving the working solution untouched for months isn't ideal although I kept my last batch going for over 18 months and it was still OK the last batch of 20 films processed.
I've now switched totally to Pyrocat HD it gives me superb negatives with modern T grain/tabular films as well as older emulsions like HP5, EFKE 25 and Fomapan 100.200, it's like Rodinal on steroids, negatives print easily they also scan well.