Vios is sub-compact while Elantra is compact. Size wise Elantra is better.
Features, Elantra is richer compared to Vios.
Fuel Consumpion, Vios is better compared to Elantra plus you need 95 octane rating for the Elantra if I am not mistaken to avoid the engine knocking issue, which is considered premium gasoline already
Parts wise, Vios is more readily available and easy to change parts at a lower price compared to the Elantra
Looks department, altough subjective, I prefer Elantra compared to the Vios.
Hope that helps.
Sir I think you are pertaining to the new accent since the new elantra doesn't have knocking issues unlike the accent.
Back to topic,
here are the pros and cons of the vios
+ cheap maintenance
+low fuel cost
+ easy to maintain
+good interior room
+value for money
+easy to drive
- small trunk size
- High levels of NVH for highway drives
- awkward driving position (for most drivers)
- getting long in the tooth so expect an all new vios in the near future
Pros and cons of the elantra
+ headturning looks (subjective)
+ smooth ride
+spacious interior and trunk
+ fuel efficient (1.6)
+ big trunk space
+ value for money
- long line to acquire a unit
- not as easy to maintain as a toyota since you have to wait for the shipment of parts
-low headroom for rear passengers
before finally deciding kindly check out the following subcompact and compact cars which might suit your budget, new lancer ex 1.6, kia rio 1.4 m/t, chevy cruze l, toyota corolla altis e, or if you can wait for a few more months check the all new ford focus which has been launched recently.