Well, I agree that the Guatemalan TList has extremely sparse information about its (way too many) entries.
However, some years ago, when I was very active looking in internet about the then existing TList sites from every country, some of the Guatemalan sites strucked me a bit more than the others. Those are:
-Tak'alik Ab'aj: I agree, it is the strongest candidate for a new WHS in that country. The Mayan-Olmec connection is unique, is highlighted by this site and the pictures of the site make it look really interesting. Additionally, it would be the only WHS in the Pacific side of Guatemala. Regarding the other TList entry "The Mayan-Olmecan" encounter"
the text under "coordinates" clearly shows that this site is a duplicate. So, no other sites besides Tak'alik Ab'aj.
-"The Painted Murals of San Bartolo": right next in order of interest, this one seems to portray an angle of the Mayan culture that isn't really in the list, and the pictures show it as interesting. Even comparing it with Mexico's own Bonampak (if it ever gets into the list), I think it still stands out.
-"Sierra de las Minas Biosphere Reservation": for its size, location (and the pictures that one can get from it), it clearly is a relatively a strong natural contendor. It is the biggest cloud forest reserve in Central America, so I think inscription would be justified.
-"The Route of the Rivers": of the rather nondescript Mayan ruin sites that are in the TList (and considering that the list has already many inscribed), this seems the most interesting one. Additionally, it is a strong chance for a binational site, with Mexico. Doing a normal search on internet will not retrieve anything about it, so I changed my search terms and found this site and map http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-25742017000100011
. The nucleus of this site would be the use of the Usumancinta river for transport, trade and the exchange of cultural influences. It would (most probably) include Guatemalan sites as Cancuén, Ceibal, Aguateca, Altar de Sacrificios and Piedras Negras and would make 100% sense if it included Mexican sites of the other site of the river: Bonampak and Yaxchilán.
-"National Park Sierra del Lacandón": another site that only makes sense as a binational site, with Mexico. But it seems to have an amazing biodiversity. Very remote, by the way.
-Naj Tunich: it may stand a chance. The information about it shows it as an ancient rock art site (again Maya, but very different from San Bartolo). I don't know how good this angle would be to achieve WH status, but it is still an angle.
-"Visis Cabá and Triángulo Ixil": I don't know too much abouth the natural angle, but maybe the three towns in the Triángulo Ixil (Santa María Nebaj, San Juan Cotzal, and San Gaspar Chajul) may have an angle to explore in a candidacy. Yes, the WH list is inundated of colonial churches, and colonial towns, but it may be made for a case for vernacular architecture and cultural exchange.
Besides that, I still find sites that could be maybe not WH experiencies at all, but that to many people I know have been very worthy tourist experiences (many Ticos travel a lot these days through Latin America and ultra-inexpensive-Guatemala really drives many people there):
-Lake Atitlán: it definitely stands out in terms of beauty, but it suffers from pollution and -if seen from a Cultural Landscape perspective- the towns on its sides have too many modern structures, so integrity has been highly affected. Still, a place I very much look forward to visit.
-"The Green Route of Verapaz": I didn't remember anything about it, but seeing the description, it includes Semuc Champey, which some friends I know have found as a worthy experience (a Pamukkale of the jungle would be it). It has only become touristy just in the last years, but they are really milking out of it these days...so...management issues may be against it.
-"Chichicastenango": yes, in terms of tangible heritage is really meagre and Dennis Nicklaus' review of it is not precisely glowing. However, on terms of intangible heritage and in the right time of the year, it could be an interesting cultural experience. Again, not WH material at all.
Regarding the other TL sites: yes, they don't stand a chance whatsoever, they present something very similar to something already inscribed or I didn't get what exact properties would be within this TL Site. Well, maybe Castillo San Felipe de Lara, but as a part of a multinational proposal, with other Central American and Caribbean forts (and still, the already certified field is really crowded).