My surname is Healy.

I've had a look over a few sites and seen many Irish renditions of the the surname (most of which were mispelled or just downright wrong).

It seems as though there are three possibilities:

Ó hÉalaighthe
Ó hÉalaithe
Ó hÉilidhe

I would contend that the first two are the same name, and that possibly the "gh" was removed after the spelling reform?

My family has strong links with Galway... anyone know which name would best suit? If the first is better fitting, then which spelling should I use?

Go raibh míle maith agaibh as aon chabhair.

According to "The Surnames of Ireland" by Edward MacLysacht, it is Ó hÉalaighthe in Munster and Ó hÉilidhe in north Connacht.
So, coming from Galway, I would guess your name would be from the latter - and comes from the words meaning 'ingenious' and 'claimant'.

Looks like I have three groups to choose from:

1

Ó hÉaladaighthe
Ó hÉalaighthe
Ó hÉalaithe

2

Ó hÉilidhe
Ó hÉilídhe (What's the craic with the fada on the "i"?)

3

Ó hÉalaí
Ó hÉilí

Using Google Fight, I got the following data:

Ó hÉaladaighthe Vs Ó hÉalaighthe: 1 : 4.105
Ó hÉalaighthe Vs Ó hÉalaithe: 1 : 8.949

Ó hÉilidhe Vs Ó hÉilídhe: 1 : 1.017 (Why?!)

Ó hÉilí Vs Ó hÉalaí: 1 : 4.574

By far the greatest found name was "Ó hÉalaí"... but I wonder if this is just a poor uninformed translation? Bad primary school teachers tend to throw around dodgy translations of surnames.

I'm still wondering about the difference between "Ó hÉalaighthe" and "Ó hÉalaithe". Would the former spelling be too pedantic (too prententious even) to use nowadays? And would "Ó hÉaladaighthe" just be down-right archaic?

I still can't figure out which surname to use! Any help?

When my father was at school, he spelt it "Ó hÉalaithe".
When I was at school, I was told to spell it "Ó hÉilí".

At the moment I'm using "Ó hÉalaighthe" but I don't know if it'd be more fitting to use one of the others?

Should I take the "gh" out of "Éalaighthe"? When the spelling reform came in, did it turn "ghth" into "th"?

You couldn't fill a mouse's teacup with what I know about genealogy, but looking at it purely as language, I notice this:

In Middle and Early Modern Irish we get new variants on the Old Irish word "élúdach" (= fugitive, survivor, escapee):

élaigthech and élaithech, which have the modern form éalaitheach, whose genitive is éalaithigh.

That accounts for group #1, and probably for the second item in group #3. "Ó hÉalaithigh", the "descendant of the survivor", seems plausible as a surname.

Your second group (and first item of the third) all involve a slender 'l', which points to a different noun entirely, one based on the Old Irish verb "éiligid" (= accuses, charges, sues, disputes), which gives us modern "éiligh" (= claim [usually legally], demand, reproach). A derived form is "éilitheach" (= demanding, importunate; solicitous), which in slightly earlier language could also be a noun meaning "one who is demanding, etc." That would give us "the descendant of the claimant, etc.", namely "Ó hÉilithigh".

For both "Ó hÉalaithigh" and "Ó hÉilithigh", the further simplifications to "Ó hÉalaí" and "Ó hÉilí" -- your group #3 -- are certainly possible as personal choices, but are probably a step too far in terms of language. After all, for the common nouns the genitives are "éalaithigh" and "éilithigh". On the other hand, these very short forms are the easiest for people to recognize and pronoun at first glance. Is tábhachtach an rud sin freisin! Tá Ó Sé i bhfad níos éasca ná Ó Séaghdha, tar éis an tsaoil!

Fútsa atá sé anois fáil amach an "survivor" nó "claimant" thusa!

Or if you know more about the history of your family before their ties in Galway. MacLysacht says that the Munster sept originated in Cork and those in Connacht from Sligo.

I got my surname from my father.

My father was born and raised in Dublin, but both his parents had moved from Galway, so my paternal grandparents are both from Galway. All four of my father's grandparents (i.e. my great grandparents) were also from Galway... so I'd say it's Galway all the way!

If I had to choose between a name originating in Sligo and a name originating in Cork, then I'd have to choose the closer one: Sligo!

So that gives me "Ó hÉilidhe". Could someone please confirm whether the spelling of this, I don't know if there should be a fada on the second "i"?

Did people change the spelling of their names when the spelling reform came in? Let's say for instance that I went with "Ó hÉalaighthe". Would people spell that like I have just there, or would they go with "Ó hÉalaithe", or would they go even further to "Ó hÉalaí"?

At the moment I'm thinking of going with "Ó hÉilidhe". It has four syllables, right? Ó Hay Lih Geh? (The "dh" is pronounced sort of like a "g", right?)

Thanks a lot for all the help.

As Dennis said, you could shorten the spelling, but you'd be doing no justice to the language. There is no fada above the second I. I believe the lenition 'dh' is pronounce as a 'g' in Munster. However, in Connacht, the slender 'dh' (coupled with i or e) is pronounced as the English Y. So, Ó HAY-lee-eh in many parts of Connacht and (At least around Galway) the final 'idhe' might be blended together as a single syllable. Giving Ó HAY-lee.