You should go for braces, only braces will close the gaps naturally. The most important thing is to find out why there are gaps, the cause for it has to be eliminated, without which the gaps can reappear even after treatment with braces and any cosmetic corrections other than braces will fail miserably if the cause is not eliminated. Cause can be predominantly a wrong bite where the lower front teeth are hitting the upper front teeth resulting in gaps in the upper front teeth, or a wrong swallow pattern leading to gaps etc .

Consult an orthodontist(braces specialist) Braces will be the permanent solution to it.Get an x ray done so that cause of midline can be identified as sometimes high labial frenum or supermerary tooth can be a cause of it. Moreover if u have other irregular teeth also ,go for braces treatment And if no such abnormality and bite is normal then you can go for LUMINEERS as well (for very small gap ).They are as thin as a contact lens and places over existing tooth without much  removal of tooth structure. Braces cost:25000 to 1.5 lakh LUMINEERS:ranging 7000 to 1 lakh per tooth

Gaps can be closed naturally by braces treatment,but it's time consuming,can be around 6-8 months, or as u said if the space is minor then u cn do a composite fillings,but those fillings can fall off after few years.or u can go for all ceramic caps on the affected teeth and get that caps corrctd.braces treatment can range from 20-1lak depending on the material u opt for like metal, ceramic or aligners. Composite fillings can range from 600-800 per tooth, where as zirconia or full ceramic cap may cost u 5k-7k each with 10-12 yrs warranty.

Braces is the better option :) if only one arch 12k treatment duration 6to 8 months, cosmetically zirconia crowns cost depends on how many needed two or four ...single crown 7k to 10k,need treatment duration 1week

Gaps between the teeth alone should not be taken as the criteria. Reason for gaps , hereditary, malformation of teeth, microdont, teeth arrangement etc have to be ruled out. After that the methods of correction must be worked out.

It totally depends on your choice for which treatment would you like to go for ... Ideally braces is the ideal solution for gaps and mal allignment of teeth ... but it takes time of few months nd costs range from 30-60 k Whereas cosmetic filling would range between 2000-3000 ... depends on your clinical condition...