So this is probably a better question for r/linguistics, and also a very subjective one… I can comment on the phonologies of late Old English and Old Norman to an extent, and the common features usually cited for these aesthetic perceptions. I am not making any absolute claims of what sounds more ‘euphoric’, or more ‘flowing’, or ‘harsher’, ‘guttural’ or ‘rougher’, but basing it on general perceptions today. I’ll speak of Old French below, but this will be taken to include Norman as well (there were differences between the Parisian and Norman French of the time, but they’re not clearly relevant here).

I would loosely (and non-definitively!) define ‘guttural’ to mean frequent use of consonants that modern English speakers would find unusually ‘throaty’, specifically velar fricatives (the ‘kh’ sound in Arabic or the ‘ch’ in ‘Bach’) and any consonants further back than velar, with the exception of glottal fricatives (h). In this sense, most varieties of French today are in fact more guttural than English, since the French ‘r’ is usually a voiced velar or uvular fricative (sometimes trill).

However, it was the other way around back then: Old English had both voiced (‘dagung’) and unvoiced (‘riht’) velar fricatives, though the voiced version was being replaced in many contexts by its unvoiced version or g by the time of the Norman Conquest. On the other hand, French was less so, as the guttural r only developed in the early modern period, and it was a trill back in the 11th century, much as it is in Spanish and Italian (and in some French dialects today).

So in that sense, yes, English may have sounded more guttural.

Two other factors that contribute to the perception of Romance languages as more ‘flowing’ than Germanic languages are the common use of glottal stops (really these come under ‘guttural’ above). This is the consonant that itself is very quiet but reveals itself in the vowels around it, as in ‘uh-oh’ or a Cockney pronunciation of ‘bottle’, but has in fact been used all the time in English throughout its history (and at least some other Germanic languages) between words where the second begins on a vowel. Where Romance speech, regardless of what sounds words started on, would sound like a continuous stream with no glottal stops at all, it’s often very clear in English where many words begin (if ‘can I’ is said emphatically, there is a glottal stop between the two words). So on this count, Old English was arguably ‘rougher’ than Old French.

The last thing to point to is that English also allows more consonant clusters, while modern French allows fewer and tends not to pronounce final consonants - but this was not always the case. Where most words in Italian, Spanish and Portuguese end on vowels due to endings like the Latin mostly feminine -a being retained and mostly masculine -us and neuter -um being reduced /u/ or /o/, French went through a stage - still seen in Occitan and Catalan - where those endings were lost as well, so that in many cases the stem remained. This in Old French many words ended in a consonant, not only on paper but as spoken. By the time or Modern French, last consonants of the stem were often lost, especially if they were plosives (and ending on plosives - like p, t, k, b, d, g sounds - is often seen as less ‘flowing’ and not doing so is often cited by those who perceive it this way as a major advantage Italian has for opera).

For example, Latin portus became portu (as in Sardinian) and then porto in Italian, Portuguese and Spanish (where the first o later became ue by another process)… but (as in Occitan and Catalan today) in Old French it was port, with the t pronounced… it is not pronounced in French today, with only the /por/ being pronounced. Due to this, Old French may be perceived as ‘rougher’ than modern French.

So broadly I would say that if you use the traits usually subjectively chosen as standards of flow and roughness commonly cited by those comparing Germanic and Romance languages, this probably still held true for Old English and Old French, but with some nuances. Hopefully the status of these three traits back then give you some idea of the differences to bear in mind from their modern descendants.