Shiba Inu is one of the best coins already traded on several exchanges. Even coins with a lot attract investors. It seems that both are long term coins as they already have a very serious and strong development team.
I can't say Shiba Inu is better or worse than Dogecoin.
In terms of long term investment, Dogecoin is more better than Shiba Inu investment because the year I tried Shiba Inu on long term investment I nearly lost all my income until I changed my strategy to start short term investment that later help me to recover all my reward. Many altcoins investors prefer to invest with Dogecoin investment base on what they have heard from other investors that showed their results they got from their short and long term investment. When others altcoin was decreasing during the month of December where was giving Dogecoin massive pumping during the process many people were looking for where to make a good profit from their business.
No no no this isn't a point mate, you buy shiba inu at a wrong time that's why you keep losing your money, maybe you FOMO when everyone are already in profits and ready to start taking profits? The fact is this can happen to any you in any coin too, timing is very important in crypto investment