The only problem with getting a HuCard only system is that if you decide to go to CD later there is no real way to move into the CDROM world and somehow take your initial investment with you. In other words, a (failure prone) CDROM attachment costs about the same as a Duo R, so your original PCE will just sit there collecting dust. I've had several PCE/TG-16s over the years but always the CD systems. The Super CD era was the one that produced the largest selection of the best (and now most affordable) games for the PCE. The initial investment in a Duo is a lot higher, but totally worth it.
On the other hand its absolutely true that HuCards should not be written off. I did this back in the day and only in recent years am I discovering how many kick-ass HuCards there are. Its just that....well, there is a big difference bewteen early PCE games like Wonder Momo and the later stuff like Sapphire. For several reasons HuCards fell out of favor with developers so there aren't as many HuCards that well represent the "later era" of PCE as there are Super CDs. For every full on, later generation HuCard soft like Bomberman '94 there are twenty Gate of Thunders.
Of course once you get hooked you won't mind having loads of multiple redundant machines.
Currently I have a PCE w/CDROM2 and Super System Card, which I love because...its just really f*cking cool, but my main "work unit" is a Duo R.
Oh, and if budget is a concern then stay away from the US stuff. In the HuCard library there are very few games worth paying the insane US premium for. Mainly Military Madness, Neutopia 1/2, and Dungeon Explorer, maybe something else (Final Lap Twin, World Court Tennis). The rest basically don't have any text worth translating anyway and in the case of many games are already in English.